Mapping and imaging of the electrical signals in the heart is typically based on combining local activation time (LAT), as indicated by a catheter's ECG signals, with the spatial position of the signals. Such a method is used in the CARTO® 3 System, produced by Biosense Webster of Diamond Bar, Calif.
Existing activity measurement algorithms are based on processing of bipolar signals which are inherently immune to far field interference. Historically, LAT is determined by the time difference between the reference annotation and the earliest activity in the bipolar signal in the mapping catheter channels. However, determining earliest activations in bipolar signals presents an ambiguity in LAT measurements since the earliest activation is a composition of the approaching fields from the two unipolar signals and does not necessarily correspond to the onset of the activity wave.
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